Propellant powders containing nitrocellulose,stabilized with certain aldehydes

ABSTRACT

A SINGLE OR MULTIPLE-BASE PROPELLANT POWDER HAVING IMPROVED BALLISTIC, MECHANICAL AND CHEMICAL PROPERTIES WHICH COMPRISES A NITROCELLULOSE OR NITROGLYCERIN BASE POWDER AND AN EFFECTIVE AMOUNT OF AN ALIPHATIC OR AROMATIC ALDEHYDE.

United States Patent Oifice US. Cl. 149-2 7 Claims ABSTRACT OF THEDISCLOSURE A single or multiple-base propellant powder having improvedballistic, mechanical and chemical properties which comprises anitrocellulose or nitroglycerin base powder and an effective amount ofan aliphatic or aromatic aldehyde.

BACKGROUND OF THE INVENTION The present invention relates to single ormultiple-base propellant powders distinguishable over conventionalpropellant powders by an improved efliciency and stability, saidpropellant powders also yielding higher initial velocities with the gaspressures being increased only to a minor extent, or not at all. Thepropellant powders of the present invention further exhibit desirableburning properties and also possess improved properties from a chemicalas well as from a ballistic point of view.

Among propellant powders, a distinction is made, as is well known in theart, between single-base powders substantially containingnitrocellulose, double-base powders containing, in addition tonitrocellulose, a further active component as the energy carrier, forexample nitration products of polyvalent alcohols, such as nitroglycerinor diethylene glycol dinitrate (DEGB), and the triple-based powderswhich contain still a third component, which in most cases is a nitrocompound. In these propellant powders a controlled deflagration takesplace during ignition, with gasses being liberated which drive theprojectile through the barrel of the firearm and out of the firearm andimpart to the projectile, at the muzzle of the barrel, a specificinitial velocity.

The propellant powders are commercially available in the form ofstrip-shaped powders as well as in the form of spherical-grain powders.The strip-shaped powders are plasticized with the use of either water orsolvents, shaped by extruding, for example, by means of a press, andthen the solvent or water is removed. In contrast thereto, thespherical-grain powders are produced with the use of a very largequantity of water, which has the advantage of a larger safety margin ascompared with the stripshaped powders produced with solvents. Thesphericalgrain powders generally exhibit a very high bulk density andaccordingly are very well suited for firearms with high efliciency(power) with a powder charge chamber which is very small.

An essential procedure during the removal of solvents and water frompropellant powders resides in a simultaneous hardening of the powdersurface. Moreover, it is likewise conventional to add stabilizers, suchas diphenylamine, to the propellant powders during the plasticizingstep, in order to bind the nitric oxides and the nitrous acid producedduring the decomposition of the degradation products of nitrocellulose,and to prevent a catalytic decomposition of the powders. Furthermore,most propellant powders are subjected to a post-treatment, because oftheir sensitivity with respect to friction, and are also exposed to asurface treatment, for example, a treatment 3,690,970 Patented Sept. 12,1972 with alkylaryl urea derivatives, urethanes, phthalates, and thelike, said compounds compressing and smoothing the surface of thepowders.

SUMMARY OF THE INVENTION An object of the present invention is to avoidthe prior art disadvantages of propellant powders.

Another object of the present invention is to provide an gniprovcdpropellant having improved efficiency and sta- 1 ity.

A further object of the present invention is to provide a hardenedsingle or multiple-base propellant powder possessing improved ballisticproperties, including an increased efficiency, an improved stability anda favorable burning velocity.

Other objects and further scope of applicability of the presentinvention will become apparent from the detailed description givenhereinafter; it should be understood, however, that the detaileddescription and specific examples, while indicating preferredembodiments of the invention, are given by way of illustration only,since various changes and modifications within the spirit and scope ofthe invention will become apparent to those skilled in the art from thisdetailed description.

Pursuant to the present invention, it has been found that theabove-mentioned disadvantages may be eliminated and a much improvedsingle or multiple-base propellant powder having improved ballisticproperties such as efficiency, stability and burning velocity, may beobtained by treating said single or multiple-base propellant powderswith aldehydes during or after their production.

Suitable aldehydes which can be used in the present invention includethe aliphatic as well as the aromatic aldehydes with the aliphaticaldehydes and particularly formaldehyde being generally preferred.Exemplary of some of the aldehydes which can be used in the presentinvention include acetaldehyde, pivalaldehyde, propionaldehyde,butyraldehyde, adipaldehyde, benzaldehyde, methylbutyraldehyde and thelike. Of course, as stated above, formaldehyde is generally preferred.

The aldehyde can be added to the crude powder mass by mixing thealdehyde, prior to shaping, with an aqueous solution of the aldehyde ina mixing device, such as a masticator-mixer. However, it is alsopossible to place the propellant powder in contact with the aldehyde inthe vapor phase prior to, during or after the drying process, byemploying the aldehydes either in a gaseous phase or as an evaporatedsolution.

The propellant powders treated with the aldehydes in accordance with thepresent invention when compared to powders which are not treated withaldehydes, exhibit a substantial improvement in their mechanical,chemical and ballistic properties. They are harder, exhibit a greaterstability, and result in higher initial velocities, with the gaspressures being increased very little or not at all. The increase intheir efliciency can be utilized either in the firearm itself or byreducing the weight of the powder in the charge.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The following examples aregiven merely as being illustrative of the present invention andaccordingly are not to be considered as limiting.

Example 1 A strip-shaped powder, consisting of:

58.5% of nitrocellulose 40.0% of nitroglycerin 0.5% ofdiethyldephenylurea 1.0% of diphenylamine 0.3% of Vaseline is allowed tostand, as a calendered sheet of foil (film), in a drying chamber for 13hours'at 50 C. A container 50 cm. high and filled with a formaldehydesolution of 38 volume percent is disposed in this drying chamber.Thereafter, the powder is further treated in the usual manner.

It is also possible to treat the finished powder with formaldehyde inthe same manner, but with a maximum temperature of about 30 C., so thatthe nubs of the already nubbed powder will not be impaired. The termnubbing of propellant powder means the impression of indentations intothe powder foil, wherein the thickness of the powder at the elevationsand depressions can be somewhat thinner than the foil (sheet). Thus, thesurface can be enlargd and the mutual spacing of the foils (sheets) fromone another can be widened.

When condutcing the above-mentioned treatment, a strip-shaped powder isobtained having the properties as set forth in the following Table 1.

TABLE 1 m, Weight of the V atmospheric Formaldehyde treatment charge, g.m./sec. gauge Without 333 309. 598 With 325 311. 6 597 Similar resultswere also observed in connection with nitroglycerin-containingspherical-type powder. In this These spherical-grain powders exhibitedthe properties indicated in the following Table 2.

TABLE 2 M, Formaldehyde Weight of the V0, atmospheric Powder treatmentcharge, g. m./sec. gauge Example 3 A single base nitrocellulose powder,which exhibited the following composition:

98.4% of nitrocellulose 1.0% of diphenylamine 4.9% of dibutyl phthalate0.6% of sodium oxalate likewise exhibited a clear increase inefiiciency, according to the following Table 3.

TABLE 3 Weight of the v t ii a mos enc Formaldehyde treatment charge, g.mJSeZ: gauge Without 49. 9 1, 034 s, 455 Wlt 49.9 1,063 3,869

TABLE 4 11b with, IIIb with,

in the He, in the H10, Ia, 11), Ha, mastieator with IIIa, masticatorWith Powder and formaldehyde treatment without with Without charge vaporwithout charge vapor Nitroglycenn, percent 39. 6 39- 4 73 40- 73 39- 540. 9 40. 9 38. 6 Diethyldiphenylurea, percent 0.65 0. 6 0.6 0. 6 0.60.6 0. 0. 6 Acetone, percent 6 0- 03 Diphenylamine, percent 1. 04 1.1 1. 0 1.0 1.0 1. 0 1.0 1.0 Ether extract, percent 41. 7 41.6 42.6 42. 641. 4 42. 6 42.6 40.6 Ex-heat, caL/g 1, 234 1, 234/46 1, 24 /46 1,241/44 1, 233/38 1, 235/39 1, 233/34 1, 237/38 Defiagration [explosion],C 160/64 164 164 165 166 TABLE 5 Upsetting P cone, Weight of atmosatmos-Recoil powder V0 pheres pheres Muzzle energy, Powder charge, g. mlsee.gauge gauge pressure I/kp.

0. 15 0. 42 I3 333 0. 27 333 0. 43 333 0. 43 325 0. 35 325 0.47 325 0.15 325 0. 52 325 O. 48 330 0. 25 330 0. 11 330 0. 10 S30 0. 13 330 0. 10330 0. 10

example, two powders, A and B, were employed having the followingcomposition:

Nitroglyoen'n, percent ca. 9 ca. 10 Diphenylamine, percent.... ca. 1 ca.1 Dibutyl phthalate, percent. ea. 5 ca. 6. 5 Ether extract, percent ca.15 ca. 18 Ex-heat, c g ca. 900 ca. 830

The amount of aldehyde which can be used in the propellant powdercomposition of the present invention is that amount which is effectivein producing a propellant composition exhibiting the advantageousresults. Advantageously a volume percent of up to about 38% and more iseffective in the present invention.

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such varia tions are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as will be apparent to one skilled in the art are intendedto be included.

What is claimed is:

1. A single or multiple-base propellant powder having improvedballistic, mechanical and chemical properties which comprises anitrocellulose or nitroglycerin base powder and an efiective amount ofan aliphatic aldehyde or benzaldehyde.

2. The propellant powder of claim 1, wherein the aldehyde isformaldehyde.

3. The propellant powder of claim 1, wherein said powder is astrip-shaped powder.

References Cited UNITED STATES PATENTS 3,244,668 4/1966 Knapp et al.26045.85 3,447,983 6/1969 Camp et al 149-98 LELAND A. SEBASTIAN, PrimaryExaminer US. Cl. X.R.

